atomSmasher

any ARM programmers in?

Does anyone still use ber and bei when dealing with bessel equations? I'm working with a book written in the twenties.

When using BSIM3V3, is connecting the bulk terminal of a MOSFET to it's source terminal the same as ignoring the body effect when deciding W/L ratios?

@ThePhoton One last question, and this might be a little far fetched, do you know if its possible to obtain (know of any good sources), or derive a MOSFETs channel width, length, and oxide thicknesses based on the values given on a datasheet? I am trying to create an accurate spice model.

I am going to chalk it up to a typo!

I constructed a common source circuit on a breadboard and the math works, but the units don't make sense!!

Sure! I am looking at Microelectronics : Circuit Analysis and Design by Neaman. The gm I am referring to is used in the textbook to determine small signal gain. ie Av = -gm(ro||Rd) = Vo/Vi. gm is derived as 2*(Kn*Idq)^1/2

Thats what I thought too, the book gives Transconductance as A/V^2

A Fairchild 2N7000

Does anyone know if the Forward Transconductance on a MOSFET datasheet is the same parameter (gm) discussed in textbooks? The units don't agree.

Are you guys any good with MOSFETS?

If I were 12 years old, would you tell me that applying 9 volts to the drain terminal of a power MOSFET and 0 volts to the gate of that FET is the equivalent of seeing a really hot girl with no clothes on? Because when I do that, my fet is too hot to touch.

hahaha nice!

@Kortuk what are the tickets for

@W5VO thanks! I am looking at the circuit below, granted they are not MOSFETS, but I don't see how circuit two provides vdd to the negative plate on cap.

Excuse my ignorance, but how does a CMOS charge pump work if the Vgs is a square wave from 0 to 5 volts?

@Dean Thank you for the link, it was very helpful!

So I have set up a little experiment which involves a HDD BLDC Motor, a scope and a multimeter. Is it possible to determine the inductance of a phase by the voltage it produces?

@tonyStewart - Do you know what the 4W1-2 stands for? I am trying to decipher if a motor controller subdivision of 1/16 is the same thing.

Ok! I will make up a question. I will post a link Tony.

@tonyStewart - I am not sure. Here is a PDF of my chip.

@tonyStewart - That is a good point. I have seen dampers used in the past. Unfortunately, this motor is not a dual shaft.

@tonyStewart crap! It seems like if I help pull the load, just a slight bit, it does ok. But it's not like I am pulling hard. I am running a 277 oz-in stepper with a 20 pitch rack and pinion (14.5 degrees). If I try and slow it down it gets worse.

@kortuk thank you. I didn't think it was possible either. I am still looking into it! I will let you know what I find.

Is it common for a stepper motor to reverse direction when the load is too much?

Looking for some tips on threading in c#. I am controlling a Rhino XR-1 arm via a phidget and load cells. I am having trouble getting things to run smoothly!